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NASA Earth Observatory images: Chaitén and Mount St Helens 30 May 2008

Posted by admin in calderas, Chaitén, Chile, eruptions, images, Mount St Helens, United States, volcanoes.
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There’s an interesting pairing of topographic views at the NASA Earth Observatory right now: a comparison of Chaitén and Mount St Helens volcanoes. The images are derived from elevation data collected by the Advanced Spaceborne Emission and Reflective Radiometer (ASTER) on NASA’s Terra satellite. The data for Chaitén were collected on 1 April 2006, before the current eruption, and the data for Mount St Helens were collected on 31 May 2007.

Comparison of Chaiten and Mount St Helens (NASA)

The images are to a uniform scale. Perhaps the most immediately striking thing is how large a feature Chaitén is, with its 2.5x4km caldera: the Global Volcanism Program calls it ‘small’, which in comparison to Santorini (12x7km), Crater Lake (8x10km), or a real monster like Toba (35x100km), is probably fair enough, but it’s still pretty sizeable. The crater left at Mount St Helens by the May 1980 eruption looks quite modest by comparison, but is nothing of the kind, of course. It was also formed in quite a different way, through a catastrophic explosion; the Chaitén caldera was formed by the volcano collapsing into its own emptied magma chamber. Except when viewed from above Chaitén is an inconspicuous part of the landscape being low in elevation, the rim reaching 1122m at its highest point. Mount St Helens, at 2549m, is more than twice its height. It’s interesting to ponder what kind and size of edifice Chaitén was before the eruption that brought about its collapse into a caldera, 10,000 or so years ago.

For all our Chaitén coverage: Chaitén « The Volcanism Blog.

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
Global Volcanism Program: Mount St Helens – summary information for Mount St Helens (1201-05-)
USGS Photo Glossary: caldera – definition, explanation and illustration of ‘caldera’ from the USGS
Global Volcanism Program: calderas – more about calderas from the GVP’s ‘Types and Processes Gallery’

The Volcanism Blog

Comments

1. Alan Sullivan - 30 May 2008

Those shadow enhanced images are beautiful but untrue to the supposed topographic scale.

2. Fresh Bilge » Chaitén Update 11 - 30 May 2008

[…] Many fine photos have become available this week, thanks to generally fair skies. The Volcanism Blog has published several photo-rich updates. One shows the ruin of Chaitén town, which is now complete, as I promised. Another shows the northbound plume of May 28, which was denser than what I see today. And a third compares pre-eruption Chaitén with post-eruption Mount Saint Helens. […]

3. Lab Lemming - 31 May 2008

Chaiten is a rhyolite volcano, and they generally have low relief as a result of being too explosive to build an edifice. Has anyone got geochem from this current eruption yet?

4. volcanism - 31 May 2008

Erik Klemetti has some compositional information at his Eruptions blog, here:

http://eruptions.wordpress.com/2008/05/30/chaiten-week-4-potential-for-dome-collapse/


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